The present relates to medical instrumentation. More particularly it relates to a micro-organism culture apparatus.
There is a growing need for the ability to rapidly determine the existance of a micro-organism in a substance such as human blood. To accomplish the detection of such organisms, a sample of the substance to be tested is placed in a culture medium, incubated, then examined after a predetermined period of incubation, for a growth of the micro-organism. This examination may be accomplished by a physical examination by an experienced operator. In other apparatus, the culture is examined optically by suitable electronic apparatus. Other means have been provided for measuring the growth of micro-organisms by means of electrodes extending into the culture liquid and detecting a change in the electrical characteristics of the liquid as a function of the micro-organism growth, or by radio isotope detection.
Those techniques which have depended upon the observation by an operator have been expensive, slow, and rely on the judgment of the human operator. Those systems which are based on electro-optical techniques are also slow. Among other things, the optical techniques require that the culture be kept mechanically quiescent to avoid obscuring the optical response wherein the detection is of a visible colony growth. The quiescent state of the culture results in a relatively slow growth of the micro-organism colonies, resulting in a relatively slow analysis program. These techniques have not been entirely satisfactory especially in the growing demands for a faster response time whereby to enable an earlier diagnosis of viable organisms.
The systems based on electronic detection of the growth have required complex circuitry complete with reference cells and bridge detectors. Some of those are not suitable for use with a blood culture because of the unavailability of the reference sample of normal blood from the same patient. Radioisotope detection systems are also slow. Further, some micro-organisms do not carry the isotope into the multiplication process. Further, none of the foregoing techniques have been subjected to a fully automated incubation and detection system.